1. The Field of the Invention
The present invention relates to cellular network amplifiers. More particularly, embodiments of the present invention relate to systems and methods for dynamically controlling a network amplifier to provide an optimal gain level and to minimize amplifier oscillation.
2. The Relevant Technology
In recent years, cellular (“cell” or “mobile”) telephones have dramatically increased in popularity. A growing number of people are relying exclusively on cell phones, and are abandoning their traditional land line telephone services in favor of the convenience of the mobility of cell phones. This increase in cell phone reliance has resulted in the need for reliable cellular signal coverage over a wider area.
Use of cell phones in areas having a weak signal often result in dropped calls which can be annoying for the cell phone user and expensive for the wireless service provider. Dropped calls typically result when the signal between the cell phone and the base station is lost. A loss of signal may occur for a number of reasons, including interference due to buildings or mountains, or an increase in distance between the cell phone and the base station. Therefore, a particular need exists to increase the reliability of cell phones near large buildings and in vehicles driving long distances in remote areas.
Attempts have been made to increase the reliability of cell phones through use of cell phone signal boosters, also known as cellular network amplifiers. Cellular network amplifiers receive the cellular signal sent from a base station, amplify the signal, and retransmit the signal to one or more cell phones. Similarly, the cellular network amplifier receives the signals from one or more cell phones, amplifies the signals, and retransmits the signals to the base station.
Cellular network amplifiers are typically placed in relatively close proximity to one or more cell phones, and serve the purpose of increasing the level of the signals being transmitted to and from the cell phones so that the cell phones can communicate with base stations that would otherwise be out of range. Some amplifiers are configured to be integrated with the cell phone itself or with a cell phone cradle. Alternatively, other amplifiers are configured to be placed in a separate location from the cell phone itself For example, a cellular network amplifier may be placed in a user's vehicle, or in or near a building that would otherwise have poor reception.
Conventional cell phone signal boosters apply constant gain levels to the signal passing through the amplifier. In general, signal boosters typically increase signal power to the maximum allowable power as permitted by the relevant governing agency. Producing this maximum regulatory allowable power can often be beneficial where the signal booster is located a long distance from the base station. However, if the signal booster is located within close proximity to a base station and the amplifier gain is too high, the signals transmitted from the signal booster may cause interference to be introduced in the surrounding cellular network by overloading the base station. Furthermore, over-amplification may also result in an unstable amplifier, causing unwanted oscillation. Both of these conditions will likely cause harmful interference to the base station and the cell phones connected to it.
The tendency for many cell phone signal boosters to cause interference creates a significant problem for wireless service providers by causing degradation to the overall quality of their service. Since wireless service providers often evaluate and approve cellular network amplifiers before they are used in the providers' systems, the providers are unlikely to approve signal boosters that cause interference.